Fatal hyperammonemia after orthotopic lung transplantation

Background: A case of fatal hyperammonemia complicating orthotopic lung transplantation was previously reported. Objective: To describe the incidence, clinical features, and treatment of hyperammonemia associated with orthotopic lung transplantation. Design: Retrospective cohort analysis. Setting: Academic medical center and lung transplantation center in Philadelphia, Pennsylvania. Patients: 145 sequential adult patients who underwent orthotopic lung transplantation. Measurements: Plasma ammonium levels. Results: Six of the 145 patients who had had orthotopic lung transplantation developed hyperammonemia, all within the first 26 days after transplantation. The 30-day post-transplantation mortality rate was 67% for patients with hyperammonemia compared with 17% for those without hyperammonemia (P = 0.01). Development of major gastrointestinal complications (P = 0.03), use of total parenteral nutrition (P < 0.001), and lung transplantation for primary pulmonary hypertension (P = 0.045) were associated with hyperammonemia. Conclusions: Hyperammonemia is a potentially fatal event occurring after orthotopic lung transplantation. It is associated with high nitrogen load, concurrent medical stressors, primary pulmonary hypertension, and hepatic glutamine synthetase deficiency.